A recent study published in the journal Earth System Science Data has found that, for reasons still not clearly understood, the global sea surface temperature reached an unprecedented high this month. Scientists are concerned that this unexpected ocean warming, combined with other weather events, could cause global temperatures to spike to a concerning new level by the end of 2024.
In addition, a strong El Niño event – a weather system which significantly heats the oceans – will likely begin over the next months, further exacerbating the current rapid ocean warming and leading to more extreme weather events, rising sea levels, die-offs of marine life, and decreased capacities of oceans to absorb greenhouse gases.
According to the experts, over the past 15 years, our planet has accumulated nearly as much heat as it did in the previous 45 years, with most of the extra energy going into the oceans.
“It’s not yet well established, why such a rapid change, and such a huge change is happening,” said lead author Karina Von Schuckmann, an oceanographer at Mercator Ocean International. “We have doubled the heat in the climate system the last 15 years, I don’t want to say this is climate change, or natural variability or a mixture of both, we don’t know yet. But we do see this change.”
Interestingly, a factor possibly influencing the amount of heat entering the world’s oceans could be a reduction in the pollution from shipping following the 2020 regulations put in place by the International Maritime Organization to reduce the sulphur content of fuel burned by ships. Although this initiative had a rapid impact in reducing the amount of aerosol particles released by ships that are polluting the atmosphere, removing them may have also caused more heat to enter the waters, since such aerosols can help reflect heat back into space.
In this context of rapid warming, the forthcoming weather phenomenon known as the El Niño Southern Oscillation (ENSO) will likely push temperatures even higher. After three years when this naturally occurring event has been in a cooler phase called La Niña – which has contributed to keeping global temperatures in check – the advent of El Niño during the following months can spell disastrous consequences for the climate, disrupting weather patterns around the globe, weakening the monsoon, and increasing the frequency and severity of wildfires in Australia.
Unfortunately, even without the further complications this weather phenomenon will bring about, the current level of ocean warming (about 0.9C above preindustrial levels) has major global consequences, including loss of species caused by marine heatwaves, more extreme weather characterized by intense and long-lasting hurricanes and cyclones, sea-level rise due to accelerated melting of glaciers that increases the risk of coastal flooding, and less ability of oceans to absorb carbon dioxide from the atmosphere.
However, according to Von Schuckmann, there is still hope left, particularly since temperatures may once more decrease after the El Niño subsides. In the meanwhile, globally coordinated efforts to mitigate climate change are essential. “We still have a window where we can act and we should use this to reduce the consequences,” she concluded.